Internal and external limb lengthening

Every technique described here cuts the bone and lengthens it gradually so that new bone forms in the gap. A published review describes methods as having evolved from external fixators to lengthening nails while resting on the same biological principles. What differs is where the device that produces the lengthening sits, and what stays in the bone afterwards.

AAOS patient information describes an external fixator connected to the bone with wires, pins or both, and worn until the bone is strong enough to support the patient safely. The Royal National Orthopaedic Hospital's patient guide names two main types: monolateral frames along one side of the limb and circular frames around it. Because pins or wires pass through the skin, Cleveland Clinic describes cleaning the pin sites every day to help prevent infection.

The external fixation method page lists providers that state this technique, and Understanding external fixation describes the frame types in more detail.

AAOS describes an expandable metal rod implanted in the bone that lengthens gradually, and Cleveland Clinic notes that it is not visible outside the body. Named systems are adjusted from outside the body in different ways: a 2021 systematic review describes FITBONE as a motorized nail and PRECICE as a magnetically driven one. Cleveland Clinic describes the device being removed in a further procedure once the new bone has hardened.

The fully internal lengthening method page lists providers that state it, and Understanding limb lengthening devices explains how named systems relate to the technique.

In lengthening over nail, as described in a 1997 clinical study, the nail and the external fixator are applied together at the time of the bone cut; after gradual lengthening, the nail is locked and the fixator removed. In lengthening and then nailing, as described in a 2008 study, the frame is used for the lengthening and a nail is inserted afterwards to support the bone while it consolidates, allowing the frame to come off. The published review describes such combined techniques as developed to shorten the period in an external frame.

The order of steps is the main difference between the two; LON and LATN: two combined techniques sets them side by side.

Where the hardware sits says nothing on its own about which technique is safer, less painful, faster or more effective for a particular person. The published review notes that internal lengthening nails avoid many of the drawbacks of external fixation but have their own complications, and that results are significantly affected by the clinical experience of the operating surgeon. The 2021 systematic review of internal nails cautions that, because no standardised method of reporting complications exists, the true complication rate might be different from the reported one.

A technique listed on a LimbAtlas profile means the provider currently names it in its own materials — not that it would be proposed or suitable for you. Technique choice depends on clinical factors that only a qualified orthopaedic surgeon can assess.